Assignment of the resonance lines in the PMR spectra of N-vinyl- and N-ethylimidazole

The PMR spectra of N-vinyl- and N-ethylimidazole were interpreted on the basis of an estimate of the broadenings and shifts of the resonance lines caused by the effect of an uncompensated electron spin of a paramagnetic complex. The site of coordination of N-vinyl- and N-ethylimidazole with NiCl₂ was established.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1416–1420, October, 1971.We thank Yu. N. Molin for his assistance in carrying out this research.     

The manifold E(0, n-m,m) in n-dimensional protective space Pn(m>2, n<m(m+1))

Ohne Zusammenfassung

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The manifold E(0, n-m, m) in n-dimensional protective space P_n(m>2, n

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Translated from Sibirskii Matematicheskii Zhurnal, No. 5, pp. 1143–1155, September–October, 1967.     

Dissipative longitudinal solitons in a two-dimensional strongly coupled complex (dusty) plasma

Solitary waves are experimentally studied in a monolayer hexagonal dust lattice which is formed from monodisperse plastic microspheres and levitated in the sheath of an rf discharge. It is found that the product of the soliton amplitude and the square of the soliton width is constant as the soliton propagates. The analytical theory describing the experiment is based on the equations of motion written for a linear chain. It takes into account damping, dispersion, and nonlinearity. The numerical simulation of a linear chain produces double solitons like those observed in the experiment.     

Atroposelective Synthesis of Axially Chiral N-Arylpyrroles by Chiral-at-Rhodium Catalysis

A transformation of fluxional into configurationally stable axially chiral N-arylpyrroles was achieved with a highly atroposelective electrophilic aromatic substitution catalyzed by a chiral-at-metal rhodium Lewis acid. Specifically, N-arylpyrroles were alkylated with N-acryloyl-1H-pyrazole electrophiles in up to 93 % yield and with up to >99.5 % ee, and follow-up conversions reveal the synthetic utility of this new method. DFT calculations elucidate the origins of the observed excellent atroposelectivity.     

Oxidation of the porous silicon surface under the action of a pulsed ionic beam: XPS and XANES studies

The changes in the electronic structure and phase composition of porous silicon under action of pulsed ionic beams have been studied by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) using synchrotron radiation. The Si 2p and O 1s core photoemission spectra for different photoelectron collection angles, valence band photoemission spectra, and X-ray absorption near-edge fine structure spectrain the region of Si L _2,3 edges of the initial and irradiated samples have been analyzed. It has been found that, as a result of the irradiation, a thin oxide film consisting predominantly of higher oxide SiO₂ is formed on the porous silicon surface, which increases the energy gap of the silicon oxide. Such film exhibits passivation properties preventing the degradation of the composition and properties of porous silicon in contact with the environment.     

Freezing and melting of 3D complex plasma structures under microgravity conditions driven by neutral gas pressure manipulation

Freezing and melting of large three-dimensional complex plasmas under microgravity conditions is investigated. The neutral gas pressure is used as a control parameter to trigger the phase changes: Complex plasma freezes (melts) by decreasing (increasing) the pressure. The evolution of complex plasma structural properties upon pressure variation is studied. Theoretical estimates allow us to identify the main factors responsible for the observed behavior.     

Leaching-out of Lanthanides from Waste Phosphosemihydrate with Sulfuric Acid Solutions of Increased Concentration

Leaching-out of lanthanides from waste phosphosemihydrate with 20–30% sulfuric acid solutions was studied.